1. Field of the Invention
The invention relates to a method and a system for inspection, and more particularly to a method and a system for image sticking inspection.
2. Description of the Related Art
A liquid crystal display (LCD) panel includes two substrates, two alignment layers, a liquid crystal layer, a plurality of electrodes, and a circuit. The circuit applies voltage to the electrodes of the LCD panel to adjust light transmittance at different regions of the LCD panel. However, the LCD panel may encounter image sticking as a result of poor circuit design or inappropriate materials being used therein.
A conventional method for image sticking inspection used by a panel manufacturer includes: displaying a checkerboard pattern using the LCD panel for a long time period, and inspecting severity of image sticking using human eyes.
Another method for image sticking inspection is disclosed in Japanese patent application publication no. 2009-294364, which includes the following steps:
providing light to the LCD panel;
applying an alternating current (AC) voltage to the electrodes of the LCD panel using the circuit thereof, such that each region of the LCD panel has a transmittance of 50%, and measuring intensity of the light passing through each region of the LCD panel;
applying a load voltage to the electrodes of the LCD panel using the circuit thereof, such that the LCD panel displays the checkerboard pattern; and
applying the AC voltage to the electrodes of the LCD panel using the circuit thereof, such that each region of the LCD panel has a transmittance of 50%, and measuring intensity of the light passing through each region of the LCD panel.
The severity of image sticking of the LCD panel can then be evaluated according to the measured intensity of the light.
However, the conventional method has the following drawbacks:
1. Even though the image sticking of the LCD panel may be evaluated as being serious, the root cause is not known to be as a result of poor circuit design or inappropriate materials being used.
2. The LCD panel must display the checkerboard pattern for a long time (about 168 hours) that is sufficient for appearance of the image sticking.
3. The LCD panel is composed of a thin-film transistor substrate and a color filter substrate. Each of the substrates is produced through 4 or 5 processes, resulting in a longer time requirement and a higher cost for image sticking inspection.